The present invention relates generally to hand saws with replaceable cutting blades and, more particularly, to a hand saw consisting of an ergonomically constructed saw blade holder with a pistol type support grip, and variations of a saw blade having a T-shaped structure for securing the blade within the grip. The support grip is designed and constructed with an elongated support having an elongated channel for receiving and supporting a particular “T” blade. Each blade configuration includes an aperture at its back end for receipt of a locking pin positioned at the back end of the support grip that engages the aperture to secure the blade in the support grip. Additionally, a trigger-like squeeze mechanism on the pistol grip rotates a rubber surfaced pad upward to contact the blade within the support grip and further secure the blade in the channel. The “T” design of the blade and support shank permits the rotation of the blades in 90° segments in order that the blade teeth can be faced in different directions that insure that a user does not have to twist their body or arm to saw. Many standard tooth styles can be utilized, i.e. hacksaw, rasp, wallboard cutter, wood etc.
In a typical hacksaw or keyhole saw the frame runs substantially parallel to the line of a narrow blade. Typically, the blade of such tools is replaced as the teeth of the blade become blunt through use, or the blade is broken. The keyhole saw is particularly useful for fretwork, hobby or craft work where precise cuts are required. The bigger version of such a tool is more bulky, but is typically used for a range of cutting procedures. The advantage of a hacksaw or keyhole saw is that the blade is replaceable when it becomes blunt or broken. This is an advantage over saws with fixed blades that, when blunted, requires sharpening, or if they get bent or structurally damaged, the saw typically has to be thrown away.
Hand tools in the past having a changeable blade were cumbersome in both releasing and securing the blades. For example, U.S. Pat. No. 2,890,732 [Westlund, Jr.] describes a saw with a saw blade holding body provided with a pistol grip. A clip on the handle can retain the lever in the flush holding position to maintain the blade locked to the handle, and a spring urges the retaining lever into the extended freeing position. A disadvantage of this system is that both releasing and securing a blade are two-step operations. To release the blade the clip must be opened and the lever flipped back; to secure the blade the lever must be swung forward and the clip closed. If the clip accidentally bumped or opened, the lever will swing out under spring force and the blade will separate from the handle. Another disadvantage is that the contact area between the retaining formation is limited so that it can loosen when worn, letting the blade move relative to the handle when locked in place.
Many of the prior handsaws used a screw or bolt to hold the blade in position. The action to release the blade was by loosening the bolt or screw. For example, U.S. Pat. No. 6,854,187 [Huan] discloses a keyless blade clamp that uses a clamping mechanism including a spring tensioned slidable block to hold a blade in place against a base plate with a round positioning protrusion mating with an aperture in the blade shank. A disadvantage to this type of clamping mechanism is that there is only a single force retaining the blade in position between the plate and spring block so that lateral forces may permit the blade to become disengaged from the clamp mechanism.
Another patent, U.S. Pat. No. 6,578,268 [Hawketts], discloses a handsaw with a retractable blade that is adjustable by a screw threaded lug or bolt, and a U-shaped cavity that holds the blade but does not grip it. A disadvantage to this device is that the blade is not capable of rotation to a different orientation; it only adjusts in length by loosening or tightening a bolt. Another disadvantage of this device is that it has a U-shaped cavity that will not hold the blade firmly in place.
Yet another patent, U.S. Pat. No. 4,248,284 [Tomosada], describes a hand saw with an interchangeable saw blade, the saw blade having a U-shaped reinforcing member, which uses a bolt to lock the blade into place. Another patent, U.S. Pat. No. 3,114,402 [Jacoff], describes a hand saw that has a rotatable blade-holding chuck, and the means for locking and unlocking the blade-holding chuck by means of a clamp and nut. Another patent, U.S. Pat. No. 2,778,395 [Forsberg], discloses a saw blade holding device which allows for a blade having an elongated slot, generally in the shape of a “T,” to be placed in any of four different directions and held in place by a T-lug that fastens the blade to the handle or gripping portion of the saw. Another patent, U.S. Pat. No. 2,773,528 [Gringer], describes a saw and saw handle that holds the blade in place by a plate clamp secured in position by a bolt. The bolt may be loosened for turning the blade and clamping mechanism and then tightened again to hold the blade in place at the rotated position.
A common disadvantage of all of the above-described devices is that the blades cannot be retained securely in place because of the use of a bolt fastening means. The bolt will tend to loosen with use causing the blade to “wobble” against the cutting force, or to displace laterally from the cutting force. Another disadvantage to using a bolt and/or screw to tighten and release the blade is that such action is a time consuming task.
Therefore, a need exists for a hand saw that locks the blade into place without the use of screws or bolts and which permits a tightly clamped fit of the blade to the handle grip. A need also exists for a hand saw that has the ability to utilize blades whose teeth can be turned to face in different directions so that a user does not have to shift his/her arm or hand to saw. A further need exists for a hand saw that ensures additional stability of the saw blade by applying pressure to the bottom of the blade during sawing.
The present invention provides an ergonomic hand held saw with unique “T” shaped blades that fit into a similarly configured channel of a handle of the pistol grip type support. The present invention also provides the user with the ability to saw in different directions while employing the normal sawing motion. The present invention's “T” shape, coupled with its position within the elongated channel, provides sufficient support to help prevent blade wobble or bending. The present invention also provides an additional trigger-like clamping mechanism located on the pistol grip, which, when squeezed, rotates a rubber surfaced pad upward through a notch in the base of the blade channel, to ensure additional stability by applying pressure against the bottom of the blade.